Trenches are dug in the ground for many purposes. Some of the purposes include laying utility and fiber optic lines, repairing such lines, and moving such lines if roadways and bridges need constructed. Also, many rural residences still use on-lot and septic systems, and problems can be encountered with such lines (cracks and blockages) that require some portion or the entire line to be dug up so that the lines can be repaired. One primary danger is that the trench walls of the trench that has been dug could collapse on the workers standing in the trench. With the acute concern for liability and consequent need to protect anyone standing for any period of time within the trench, some type of apparatus is needed to support the trench walls for enhancing the safety and security of anyone standing and working within the trench.
A typical trench support consists of two pieces of steel plate interconnected by support rods that have been welded to the interior sides of the steel plates. Such makeshift support is heavy, difficult to maneuver in the trench for moving and repositioning as the workers move along the length of the trench, and awkward to transport and store as it cannot be broken down for easy and compact storage and transport.
The prior art discloses a variety of shoring, excavation, and support structures for trenches and excavations.
For example, the Fisher patent (U.S. Pat. No. 4,056,940) discloses a trench box height adaptor that includes spaced walls from which tubular collar project and into which spreader pipes are inserted for spacing and interconnecting the spaced walls.
The Nieber patent (U.S. Pat. No. 4,090,365) discloses a portal frame for a trench box stack that includes an adjustable trench box structure whose depth is adjustable to allow for the clearance of conduit and pipe.
The Birchfield patent (U.S. des. Pat. 252,950) discloses a design for a lightweight trench box that includes spacing pipes mounted to interiorly projecting collars.
The Cook patent (U.S. Pat. No. 4,259,028) discloses a water and debris impermeable trench box panel wherein each panel includes a lightweight foamed filler.
The Ischebeck et al. patent (U.S. Pat. No. 4,752,157) discloses a trench shoring box unit that includes partition walls spaced from each other and supported by adjustable length braces.
The Collins patent (U.S. Pat. No. 4,993,880) discloses a trench-box panel that includes a pair of opposed arrays of elongated horizontal members with the horizontal members of each array having their ends staggered to accommodate angle members and flat members that support struts that space the arrays from each other in the trench.
The Spencer patent (U.S. Pat. No. 5,310,290) discloses a protective structure for excavations that includes a pair of protective panels constructed of corrugated aluminum sheet and which is retained in their spaced-apart relations by a plurality of spreader beams.
The Wilkinson patent (U.S. Pat. No. 5,931,608) discloses a trench shoring transport device that includes a frame assembly movable on wheels and from which depend one or more trench boxes that can be lowered into place by hydraulic vertical members.
The Kadiu patents (U.S. patents/application publication no.s 2004/01700478 A1, 7,048,471 B2, and 7,056,067 B2) discloses shoring devices for trenches and rectangular and polygonal pits and which includes a pair of shoring panels with each panel having vertical struts mounted to their opposed ends and at least one strutting assembly mounted to the opposed vertical struts of the panels for spacing the panels from each other and maintaining the panels in their spaced relation.
Nonetheless, despite the ingenuity of the above devices, there remains a need for a lightweight trench support having support plates whose spacing from each other is adjustably accomplished by extendible and retractable slidably adjustable support arms.